Access Device

ABSTRACT

A device may include a hollow needle, a dilator mounted coaxially on the needle, and a sheath mounted coaxially on the dilator. The dilator may be slideably displaceable relative to the sheath.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.10/329,173, filed Dec. 24, 2002, hereby incorporated herein byreference, which claims the benefit of U.S. Provisional Application No.60/343,814, filed Dec. 26, 2001.

FIELD OF THE INVENTION

This invention is directed to vascular access. More particularly, thisinvention is directed to a vascular access device that is easier, safer,and faster to use than prior such devices.

BACKGROUND OF THE INVENTION

A preferred non-surgical method for inserting a catheter or vascularsheath into a blood vessel involves the use of the Seldinger technique,which includes an access needle that is inserted into a patient's bloodvessel. A guidewire is inserted through the needle and into the vessel.The needle is removed, and a dilator and sheath combination are theninserted over the guidewire. The dilator and sheath combination is theninserted a short distance through the tissue into the vessel, afterwhich the dilator is removed and discarded. The catheter is theninserted through the sheath into the vessel to a desired location. Anumber of vascular access devices are known. See, for example, U.S. Pat.Nos. 4,581,019, 4,629,450, 4,772,264, 4,978,334, 5,158,544, 5,424,410,5,312,355, 5,512,052, 5,728,132, 5,885,217, 5,919,160, 6,120,494,6,179,823, and 6,210,366, each of which is incorporated herein byreference, wherein various devices for vascular access are described.However, none of these devices has the ease and safety of use thatphysicians would prefer, and there is thus a need for an easier-to-useand safer vascular access device, especially one that would clearlyindicate when a blood vessel has been punctured.

OBJECTS OF THE INVENTION

It is an object of the invention to provide vascular access.

It is also an object of the invention to provide easier, safer, andfaster vascular access.

It is additionally an object of the invention to provide a vascularaccess device that eliminates the possibility of inadvertent guidewiremisplacement into the vascular system during the vascular accessprocedure.

It is a further object of the invention to provide a method ofintroducing catheters or other medical devices in an easier, safer, andfaster procedure, where the appearance of a patient's blood in thevascular access device indicates to the practitioner that the needle hasaccessed the desired vessel.

These and other objects of the invention will become more apparent inthe discussion below.

SUMMARY OF THE INVENTION

According to the invention, a dilator or a sheath and dilator aremounted on a needle, which needle has a lateral opening proximal to theneedle distal tip. Prior to insertion, the needle is positioned so thatthe distal end of the needle is distal to the distal end of the dilator.After insertion of the needle into a blood vessel, the needle openingpermits blood to flow into an annular space in the dilator or betweenthe needle and the dilator to indicate that the distal end of the needlehas punctured the blood vessel. Additionally or alternatively, bloodflows into an annular space formed by the sheath to indicate that theblood vessel has been punctured. In addition, blood may flow to anoptional side port to provide further indication access has beenachieved.

Once vascular access is achieved, that is, once the distal tip of theneedle punctures a blood vessel and blood flows through a lateralopening in the needle to one of the annular spaces described above andas appropriate, into a side port, a guidewire is threaded through theneedle, and then the entire apparatus, including the needle, thedilator, and a sheath, can be advanced over the guidewire into the bloodvessel. At a desired time the sheath, needle, and dilator can beadvanced over the guidewire. When the sheath is in position, the innerdilator, needle and guidewire can be removed together. Thus, theguidewire protects the needle tip, and the needle, with the guidewire init, can then be bent for added safety, to prevent removal of theguidewire and consequential exposure of the needle tip. Alternatively,the guidewire can be left in place for catheter placement.

In one embodiment of the invention, the dilator has a distal member thatcan be advanced distally or the distal tip of the needle can beretracted so that the distal tip of the dilator distal member extendsdistally over the distal tip of the needle. The dilator distal memberthen protects the blood vessel wall as the needle, dilator or needle,dilator, sheath are advanced or withdrawn from a blood vessel,preferably over a guidewire. In addition, when the needle, dilator orneedle, dilator, sheath are pulled out, the healthcare worker isprotected.

In another embodiment of the invention, there is a coaxial dilatorsystem, with an inner dilator and an outer dilator. The inner dilatorcan be advanced independently distally to the distal tip of the needle.The inner dilator then covers the needle tip, the inner dilator distalmember then protects the blood vessel wall as the needle, dilator or theneedle, dilator, sheath are advanced or withdrawn from a blood vessel,preferably over a guidewire. In addition, when the needle or needle,dilator, and/or sheath are pulled out, the worker is protected.

In another embodiment of the invention the needle can be rotatedrelative to the dilator or the dilator and sheath, so that the needletip, which is inserted into a blood vessel with the needle distal tipbevel up, can be rotated 180° so that the needle distal tip bevel isdown. When the needle distal tip is in this position, it is less likelythat movement of the needle distal tip will cause injury to the bloodvessel. The proximate portion of the needle member may have colorcoding, words, or other indicia to indicate the relative position of theneedle tip level. Also, the needle member proximal portion may have anotch, pivot, indent, or other mechanism to indicate relative positionand/or to hold the needle member in position relative to the dilator orthe dilator and sheath.

The vascular access device of the invention has several uses, includingaccess to every vessel when a vascular sheath is needed as in stentplacement, Percutaneous Transluminal Coronary Angioplasty (PTCA), etc.or when a peel-away sheath is needed, for example, for inserting PICClines, pacemaker leads, etc. In addition, the invention would be usefulfor access to dialysis grafts and fistulas, which are superficialstructures and where access is sometimes needed quickly, especiallyduring a de-clotting procedure. Another use would be for placement ofcentral lines (subclavian or internal jugular). Instead of use of alarge (18 G) needle (current technique), followed by advancement of adilator over a guidewire and exchanging it for a triple lumen catheteror vascular sheath, according to the invention a large needle or a smallneedle can be used to gain vascular access with a vascular sheaththrough which a triple lumen or any other catheter can be safely placed.

The present invention has several advantages, the first of which is itsefficiency. Instead of the current multi-step access method with anexchange of guidewires and sheaths, this invention reduces the number ofsteps and simplifies access. Another advantage is safety. After a vesselis accessed, the guidewire can be left in to protect the needle tip. Theneedle, dilator and guidewire can be removed together after the sheathis in place. If no additional access is needed in the same procedure,the needle can be bent for added safety. This is contrary to the currenttechnique where the unprotected bloody needle is removed from theguidewire after vascular access is gained. Alternatively, the guidewirecan be left in place to provide further access through the sheath andthe dilator distal member protects the distal tip of the needle andultimately the user. Another advantage is the reduction of infection. Byminimizing the number of guidewires and sheaths necessary to obtainvascular access, the opportunities for inadvertent contamination aredecreased. A further advantage is that under non-hospital or fieldconditions, use of the invention will decrease the possibility ofinfection due to a non-sterile environment. A yet further advantage isthe added stiffness of the system. The added stiffness provided by theneedle is enabling advancement of the system without multipledilatations and reduced trauma to the patient.

An even further advantage relates to the bleeding from the needle, thedilator, and around the wires that occurs during guidewire exchangeswith current techniques. Such bleeding increases the spread of bloodover the surgical field and the operator's gloves, thereby, increasingthe chance of infection in case an inadvertent needle stick happens. Thedevice of the invention will decrease this risk of infection because theblood will flow into the sheath rather than into the surgical field asin the current technique.

Another and further advantage of one embodiment of the invention, isthat there is no need for over-the-wire exchanges. The device can beconfigured to eliminate the possibility of inadvertent guidewiremisplacement into the vascular system during the access procedure. Inthe current technique, with exchange of the needle for a dilator andthen for the sheath, it is a known complication that the operator failsto grasp the guidewire during those exchanges and the guidewire isinadvertently advanced with the dilator or catheter into the patient'svascular system. The guidewire then has to be removed either surgicallyor snared percutaneously.

Lastly, the present invention will be cost-effective. The system of theinvention will eliminate the need for an additional guidewire andcoaxial dilator to be used in gaining vascular access.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 and 2 are each a schematic representation of one embodiment ofthe invention;

FIGS. 3 and 4 are each a schematic representation of another embodimentof the invention;

FIG. 5 is a partly cross-sectional view of a further embodiment of theinvention;

FIG. 5A is a cross-section along line 5 a-5 a;

FIG. 6 is a partly cross-sectional view of another aspect of theinvention;

FIG. 7 is a partly cross-sectional view of a further aspect of theinvention;

FIG. 8 is a partly cross-sectional view of an embodiment of theinvention where the distal portion of the dilator extends distally;

FIGS. 9A to 9C are schematic representations of use of the embodiment ofthe invention shown in FIG. 8;

FIGS. 10A and 10B are schematic representations of an embodiment of theinvention with a coaxial dilator system; and

FIG. 11 is a schematic cross-sectional view of the proximal portion ofthe system of FIGS. 10A and 10B.

DETAILED DESCRIPTION OF THE INVENTION

The invention can perhaps be better appreciated from the drawings. InFIGS. 1 and 2 a needle section 102 comprises a needle 104 and a proximalportion 106 with a twist lock member 108, and a dilator section 112comprises a dilator 114 and a hub 116. In a preferred embodiment of theinvention, needle 104 has one or more openings 120. Dilator 114 ispreferably clear, semi-opaque, or translucent so that when blood flowsinto needle 104 and then through an opening 120 either (1) into anannular space 122 between needle 104 and dilator 114 or (2) into orthrough spaces (not shown) in dilator 114, the physician can see theblood. This will indicate to the physician that the distal end 124 ofneedle 104 has punctured a blood vessel (not shown).

As can be seen in FIG. 2, dilator hub 116 releasably engages needleproximal section 106. Here, dilator hub 116 comprises a conical recess117 that receives a conical member 119 forming a part of needle proximalsection 106. Needle proximal section 106 comprises an annular portion121 having threading 123 that engages reciprocal threading 125 on hub116. Other arrangements of threading, detents, or other snap- orforce-fit configurations that achieve the same purpose of releasablyengaging the proximal portions of the needle and dilator sections arealso within the scope of the invention.

Hub 116 may optionally have a porous vent 128. Needle proximal portion106 may optionally have a porous vent plug 130 that fits a channel 132in fluid communication with lumen 134 of needle 104, recess 117, andneedle proximal portion 106 having lumen 136.

Needle proximal portion 106 may have color coding, words, or otherindicia, such as a pivot or notch, to indicate to the operator theposition of the bevel of distal tip 124 relative to dilator 114. Also,there may be a mechanical fit between dilator 114 and needle 104 so thatthe operator would sense by feel or sound when the needle has beenrotated to change the position of the needle tip bevel.

In the embodiment of the invention shown in FIGS. 3 and 4, a needlesection 142 comprises a needle 144 and a proximal portion 146 with atwist lock member 148, a dilator section 150 comprises a dilator 152 anda hub 154, and a sheath section 160 comprises a sheath 162 and aproximal portion 164. In a preferred embodiment of the invention, needle144 has one or more openings 149. Dilator 152 and sheath 162 arepreferably clear, semi-opaque, or translucent so that when blood flowsinto needle 144 and then through opening 149 (1) into an annular space170 between needle 144 and dilator 152, (2) into or through spaces (notshown) in dilator 152, or (3) through an opening 172 into an annularspace 174 between dilator 152 and sheath 162, the physician can see theblood. As above, this will indicate to the physician that the distal end176 of needle 144 has punctured a blood vessel (not shown). Preferablysheath proximal portion 164 has a port 178 so that blood can be aspiredthrough a syringe (not shown). The sheath may contain a hemostatic valve(not shown) in the distal end 164 to prevent blood flow out the distalend of the sheath.

Proximal sections 108 and 116 and 146 and 154, respectively, mayoptionally have luer connecting members. For example, section 108 mayhave a male luer lock 129, and section 116 may have a female luerconnector 131. Sections 146 and 154 may have comparable members,respectively.

As shown in FIG. 4 sections 142, 150, and 160 can be inserted into oneanother. Proximal sections 146, 154, 164 can twist or snuggly fittogether, such as with a luer connector, threading, a pressure or snapfit, a detent/groove arrangement, or a combination thereof. Thestructure shown in FIG. 2 is especially applicable here.

In another embodiment of the invention as shown in a partialcross-section in FIG. 5, needle 180 has an opening or side hole 182.Dilator 184, which is arranged coaxially to needle 180, has asubstantially hollow distal section 186 and a substantially solidproximal section 188, which sections 186 and 188 are connected by rigidor substantially rigid longitudinal members 190, to form an interruptedor discontinuous structure. The space between sections 186 and 188 notoccupied by members 190 constitutes an annular or substantially annularspace 194, into which blood can flow from opening 182. Sheath 196 istransparent or translucent, so that the blood in space 194 can beobserved by the physician.

Preferably dilator 184 has one or more small openings, pores, or porousmaterial 200, for example, in sheath 196, to allow air or gas to leaveannular space 194 as blood enters. The openings themselves, or theopenings in the porous material, are small enough that air will escapebut blood will be retained. Suitable porous materials include a porouspolymer such as self-sealing, white porous HDPE of pore size 2.5microns.

The distal end 202 of a guidewire 204 is preferably preloaded, that is,positioned within a lumen 206 of needle 180. In this way blood will flowinto needle 180 and out through opening 182, and not proximally outlumen 206. Once the physician sees the blood in annular space 194,guidewire 204 can be advanced distally through lumen 206 into a bloodvessel (not shown). Another view of the relationship between needle 180,dilator longitudinal members 190, and sheath 196 can be seen in thecross-sectional view shown in FIG. 5A.

Separate designs for a dilator member according to the invention areshown in more detail in FIGS. 6 and 7. In FIG. 6, a dilator 210 shownhas conical elements. A distal dilation section 212 comprises a doublecone design with a passageway 214 extending from the tip of one conicalelement 216 to the tip of another conical element 218. At least twostabilizing longitudinal members 220 extend from distal section 212 to aproximal section 222, which preferably comprises a single conicalelement 224 with a passageway 226 and a proximal twist or lockingsection 228.

The embodiment of the invention shown in FIG. 7 comprises adilator-needle combination where the dilator device described in FIG. 6also comprises a needle 232 that extends through passageway 214 to andthrough passageway 226. Needle 232 has a proximal section 234 thatcomprises a twist or locking arrangement.

In the partial representation of an embodiment of the invention shown inFIG. 8, a dilator 240 is arranged circumferentially around a needle 242.Dilator 240 has a distal portion 244 that extends distally toward thedistal tip 246 of needle 242. Alternatively, the inner, elongateddilator is coaxially located within the larger outer dilator. The innerelongated member can be advanced over the needle to protect the tip. Asdepicted in FIGS. 9A to 9C, a needle 252 is positioned in a punctureopening 254 in a blood vessel 256. A guidewire 258 extends distally fromneedle 252 into a lumen 260 of blood vessel 256. A dilator 262positioned circumferentially around needle 252 has a distal portion 264.As shown in FIG. 9B, dilator distal portion 264 can be advanced overneedle 252 so that the distal tip 268 of dilator distal portion 264extends distally of the distal tip 270 of needle 252. Then, when, asshown in FIG. 9C, needle 252 and dilator 262 are advanced distally overguidewire 258, needle distal tip 270 is protected by dilator distalportion 264.

The embodiment of the invention shown in FIGS. 10A and 10B comprises acoaxial dilator system comprising inner dilator 276 and outer dilator278. Dilators 276 and 278 are arranged around needle 280, and the distalend 282 of inner dilator 276 is initially slightly distal of the distalend 284 of outer dilator 278. The proximal end (not shown) of innerdilator 276 is advanced distally to cause inner dilation distal end 282to cover the distal end 288 of needle 280. Preferably dilators 276 and278 interact or are held so that they retain their relative positionswith regard to each other and needle 280 as the needle, dilator orneedle, dilator, sheath combination is advanced into or withdrawn from ablood vessel (not shown), optimally over a guidewire (not shown).

The coaxial dilator system shown in FIGS. 10A and 10B requires anactivation system that causes one dilator to move in relation to theother dilator. It is preferred that the inner dilator would be advanceddistally to cover the distal end of the needle while the outer dilatorremains constant, or in place. Preferably the dilator system would beconfigured so that the outer dilator would remain relatively,substantially in place while the inner dilator is pushed, pulled, orslid in the distal direction. In the embodiment shown in FIG. 11, aproximal needle section 290 is circumferentially surrounded by aproximal inner dilator section 292 and an outer dilator section 294.Tapered needle hub 296 has at least one annular projection or ring 298that is received in an annular groove 302 in the tapered outer dilatorproximal hub 304. Inner dilator hub 306 has threading 308 that engagesreciprocal threading 310 on needle 290 or on a separate needle memberattached to needle 290 or needle hub 296. Inner dilator hub 304 has aprojection or wing 312 that moves within, and is guided by, a slot 316that prevents rotation of inner dilator 292 with respect to outerdilator 294. It is within the scope of the invention that othermechanical arrangements known or discernible to those skilled in the artwould be acceptable, so long as they permitted advancement of the distalportion of the inner dilator over the distal portion of the needlewithout rotation of the inner dilator relative to the outer dilator.

The invention herein is comprised of conventional, physiologicallyacceptable materials. For example, the needle consists of a rigidpolymer or a metal such as stainless steel, nitinol, or the like. Theother elements will typically consist of suitable polymeric materials,such as polyethylene, polypropylene, fluoropolymers and copolymers suchas perfluoro (ethylene-propylene) copolymer, polyurethane polymers orco-polymers.

The preceding specific embodiments are illustrative of the practice ofthe invention. It is to be understood, however, that other expedientsknown to those skilled in the art or disclosed herein, may be employedwithout departing from the spirit of the invention or the scope of theappended claims.

1. A device comprising: a hollow needle having a bore and a sharpeneddistal tip and defining a side hole proximal to the distal tip; aguidewire so sized as to be slideable in the needle bore; a dilatorcoaxially mounted on the needle thereby defining a first space betweenthe dilator and needle, the first space communicating with the hollowneedle bore through the side hole so that a fluid, if any, exiting theside hole may flow to the first space; and a sheath coaxially mounted onthe dilator, thereby defining a second space between the sheath and thedilator or between the sheath and the needle; wherein at least one ofthe dilator and sheath is clear, semi-opaque, or translucent, so thatfluid, if any, in at least one of the spaces, may be visualized throughthe dilator and/or sheath to confirm proper placement of the needle in acavity containing the fluid; and wherein the dilator is slideablydisplaceable relative to the sheath.
 2. The device of claim 1, whereinthe sheath is a peel-away sheath.
 3. The device of claim 1, wherein thesheath comprises a catheter.
 4. The device of claim 3, wherein thecatheter is a multi lumen catheter.
 5. The device of claim 1, whereinthe dilator and sheath are slideably displaceable together over theneedle.
 6. The device of claim 1, wherein the needle, dilator, andsheath are slideably displaceable together over the guidewire.
 7. Thedevice of claim 1, wherein the dilator is slideably displaceable overthe needle to a position in which it covers the needle's sharpeneddistal tip, thereby protecting it.
 8. The device of claim 1, wherein thedilator is clear, semi-opaque, or translucent, so that fluid, if any, inthe first space may be visualized to confirm proper placement of theneedle in the cavity.
 9. The device of claim 1, wherein the sheath isclear, semi-opaque, or translucent, the second space communicates withthe first space, so that fluid, if any, in the second space may bevisualized to confirm proper placement of the needle in the cavity. 10.The device of claim 1, wherein the dilator comprises a discontinuousstructure having a solid distal section connected to a solid proximalsection by at least one longitudinal member, so that the second space isdefined between the sheath and the needle and the second spacecommunicates with the hollow needle bore through the needle side hole,so that fluid, if any, in the second space may be visualized through thesheath to confirm proper placement of the needle in the cavity.
 11. Thedevice of claim 1, wherein the dilator comprises a continuous tubestructure, so that the second space is defined between the sheath andthe dilator, and so that fluid, if any, in the second space may bevisualized through the dilator and the sheath to confirm properplacement of the needle in the cavity.
 12. The device of claim 1,wherein the sheath comprises a side port.
 13. The device of claim 1,wherein the sharpened distal tip of the hollow needle protrudes distallyfrom the dilator.
 14. The device of claim 13, wherein the cavity is acentral blood vessel of a patient, and the sharpened distal tip of thehollow needle so protrudes distally from the dilator as to reach thecentral blood vessel of the patient.
 15. The device of claim 13, whereinthe cavity is a peripheral blood vessel of a patient, and the sharpeneddistal tip of the hollow needle so protrudes distally from the dilatoras to reach the peripheral blood vessel of the patient.
 16. The deviceof claim 1, wherein the hollow needle is so stiff as to support thedilator and sheath during advancement of the device into the cavity. 17.The device of claim 1, wherein the dilator defines a dilator side hole,and wherein the first space communicates with the second space throughthe dilator side hole, so that fluid, if any, exiting the dilator sidehole may flow to the second space.
 18. The device of claim 1, whereinthe dilator is at least partly semi-opaque, and the sheath is at leastpartly clear or translucent.
 19. The device of claim 1, wherein a distalend of the guidewire is preloaded in the needle, and the guidewirefurther comprises a proximal free end.
 20. The device of claim 1,wherein the dilator comprises a distal dilation section having a doublecone configuration.
 21. The device of claim 1, further comprising a sealdisposed between the dilator and sheath.
 22. The device of claim 1,wherein the sheath comprises a hemostatic valve.
 23. The device of claim1, wherein the needle is attached to a proximal needle hub, the dilatoris attached to a proximal dilator hub, and the needle hub and dilatorhub are interlockable with one another.
 24. The device of claim 1,wherein the dilator is attached to a proximal needle hub, the sheath isattached to a proximal sheath hub, and the dilator hub and sheath hubare interlockable with one another.
 25. The device of claim 1, whereinthe dilator is affixed to the needle.
 26. A kit comprising the device ofclaim 1 and a catheter.
 27. The kit of claim 26, wherein the catheter isa central line.
 28. The kit of claim 26, wherein the catheter is aperipherally inserted central catheter (PICC).
 29. A device comprising:a hollow needle defining a side hole and having: a bore so sized as toreceive a guidewire; and a sharpened distal tip distal to the side hole;a dilator coaxially mounted on the needle thereby defining a first spacebetween the dilator and needle, the first space communicating with thehollow needle bore through the side hole so that a fluid, if any,exiting the side hole may flow to the first space; and a sheathcoaxially mounted on the dilator, thereby defining a second spacebetween the sheath and the dilator or between the sheath and the needle;wherein at least one of the dilator and sheath is clear, semi-opaque, ortranslucent, so that fluid, if any, in at least one of the spaces, maybe visualized through the dilator and/or sheath to confirm properplacement of the needle in a cavity containing the fluid; and whereinthe dilator is slideably displaceable relative to the sheath.
 30. A kitcomprising the device of claim 29 and a guidewire.
 31. The kit of claim30, further comprising a catheter.
 32. A method comprising: with thedevice of claim 29, introducing the distal tip of the hollow needle intoa cavity; threading a guidewire through the distal tip of the needleinto the cavity; advancing the dilator and sheath together over theneedle into the cavity; and removing the guidewire, the needle, and thedilator, thereby leaving the sheath in place to provide access to thecavity.
 33. The method of claim 32, wherein advancing further comprisesadvancing the needle together with the dilator and sheath in to thecavity over the guidewire.
 34. The method of claim 32, wherein at leastone of the dilator and sheath is clear, semi-opaque, or translucent, sothat fluid, if any, in at least one of the first and second spaces, maybe visualized through the dilator and/or sheath, and the method furthercomprises confirming proper placement of the needle by visualizing fluidin at least one of the first and second spaces through the dilatorand/or sheath.
 35. The method of claim 34, wherein the dilator is clear,semi-opaque, or translucent, and the method further comprises confirmingproper placement of the needle by visualizing fluid in the first space.36. The method of claim 34, wherein the sheath is clear, semi-opaque, ortranslucent, the second space communicates with the first space, and themethod further comprises confirming proper placement of the needle byvisualizing fluid in the second space through the sheath.
 37. The methodof claim 34, wherein the dilator comprises a discontinuous structurehaving a solid distal section connected to a solid proximal section byat least one longitudinal member, so that the second space is definedbetween the sheath and the needle and the second space communicates withthe hollow needle bore through the side hole, and the method furthercomprises confirming proper placement of the needle by visualizing fluidthrough the sheath.
 38. The method of claim 34, wherein the dilatorcomprises a continuous tube structure, so that the second space isdefined between the sheath and the dilator, and the method furthercomprises confirming proper placement of the needle by visualizing fluidthrough the dilator and sheath.
 39. The method of claim 34, wherein thefluid comprises blood, and proper placement is confirmed, beforeadvancing the dilator and sheath, by observing a blood flash through thedilator and/or sheath.
 40. The method of claim 32, wherein the sheathcomprises a side port, and the method further comprises sampling fluidfrom the cavity through the side port.
 41. The method of claim 32,wherein the fluid comprises blood.
 42. The method of claim 41, whereinthe cavity comprises a blood vessel.
 43. The method of claim 42, whereinthe blood vessel is a central blood vessel.
 44. The method of claim 43,wherein introducing comprises introducing the distal tip of the hollowneedle into the patient's central blood vessel without the dilatorpenetrating the patient's skin.
 45. The method of claim 41, furthercomprising observing a blood flash before advancing the dilator andsheath.
 46. The method of claim 32, further comprising supporting thedilator and sheath with the hollow needle during advancement.
 47. Themethod of claim 32, wherein the dilator is so advanced over the needleas to contain the needle distal tip within the dilator to protect theneedle distal tip.
 48. The method of claim 32, further comprisingadvancing a medical device through the sheath.
 49. The method of claim48, wherein the medical device comprises a catheter.
 50. The method ofclaim 49, wherein the cavity is a blood vessel, the fluid is blood, andthe medical device comprises a central catheter.
 51. The method of claim50, wherein the central catheter is a peripherally inserted centralcatheter (PICC).
 52. A device comprising: a hollow needle defining aside hole and having: a bore so sized as to receive a guidewire; and asharpened distal tip distal to the side hole; a dilator coaxiallymounted on the needle thereby defining a first space between the dilatorand needle, the first space communicating with the hollow needle borethrough the side hole so that a fluid, if any, exiting the side hole mayflow to the first space; and a sheath coaxially mounted on the dilator;wherein at least one of the dilator and sheath is clear, semi-opaque, ortranslucent, so that fluid, if any, inside the device, may be visualizedthrough the dilator and/or sheath to confirm proper placement of theneedle in a cavity containing the fluid; and wherein the dilator isslideably displaceable relative to the sheath.